The present invention generally relates to improvements in beam splitters and optical imaging systems.
In general, spatial filtering or spatial frequency modulation has been employed for many years to remove or reduce the appearance of artificial pixel or line structures in television, computer, electronic camera, and half-tone images, which structures otherwise decrease overall image fidelity. In the specific case where images are comprised of many dots or lines, this spatial modulating is most commonly implemented by splitting the image into two components and slightly shifting them relative to each other to blend these structures. In terms of image processing, such an approach effectively modulates the spatial frequency spectrum of the image with a cosine function to suppress the harmonic frequencies of the generally repetitive artificial structures of the camera or display. In a camera system, this results in improved color fidelity as well as a general reduction in aliasing and moire effects. In a display system, this results in the general expansion of discrete line and picture elements to form a more seamless, solid look.
For optical image modulation to be practical it must result in minimum impact on the conventional optical system of the imaging device. This is commonly achieved with a thin optical modulator incorporating a beam splitter component having a fixed, repeating, triangular-wave surface structure formed thereon, wherein the amount of image splitting is dependent on the structure's alternating slopes.
While such arrangements constitute a certain amount of improvement in image fidelity, modulator arrangements using triangular and other fixed-structure image modulators suffer from the drawback that they require expensive tooling for each design. Since each imaging system may conceivable require a different amount of modulation, accommodating the diverse imaging industry with a full range of modulators represents an unwarranted tooling expense. In addition, many imaging systems employ a zoom lens which can directly effect the amount of splitting required, significantly diminishing the benefit of modulation with any departure from the single optimum configuration.